DoE Review Template

1
Schematic View of the MINOS Scintillator System
Scintillator Module

• Extruded scintillator, 4.1 cm wide
• Two-ended WLS fiber
• readout.
• Strips assembled into
• 20 or 28-wide modules.
• WLS fibers routed to
• optical connectors.
• Light routed from modules
• to PMTs via clear fibers.
• 8 Fibers/PMT pixel in far
• detector. (Fibers separated
• by 1m in a single plane.)
• 1 Fiber/PMT pixel in near
• detector (avoids overlaps).
• Multi-pixel PMTs
• Hamamatsu M16 (far), M64 (near)

WLS Fibers
WLS Fibers
8 m
Optical Connector
Optical Connector
Clear Fiber Ribbon Cable (2-6 m)
Clear Fiber Ribbon Cable (2-6 m)
Optical Connector
Optical Connector
Connection to electronics
Multiplex Box
Multiplex Box
Connection to electronics
PMTs
Objects not to scale
2
Far Detector Module Layout

• 8 modules cover one far detector steel plane
• Four 20-wide modules in middle (perp. ends)
• Four 28-wide modules on edges (45 deg ends)
• Two center modules have coil-hole cutout

28
Coil Bypass
3
Near Module Layout
New Picture In Development
Some changes under study.
4
Extruded Scintillator
Light output measurements in Aug. 2000
Photo of a scintillator strip
Typical light yield in Nov. 2000
Cross-section photo of two scintillator strips
with fibers glued into grooves.
As long as desired
Problems found and fixed!
Rapid light output checks are important to
establish and maintain high quality
10 mm
41 mm

• Dow Styron 663 W polystyrene without additives
• PPO and POPOP waveshifters (1 and 0.03 by
  weight)
• 1.0 cm x 4.1 cm cross-section extrusion
  co-extruded with TiO2 reflector
• Extruded groove for WLS fiber (which is glued
  into the strip)
• Light output excellent for this collection
  geometry better than
• commercial cast scintillator machined to shape
  and wrapped with Tyvek.

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WLS Fiber

• Kuraray WLS fiber
• 1.20 0.024 -0.005 mm diam.
• 175 ppm Y11 fluor (K27)
• polystyrene core, double clad (PMMA and
  polyfluor)
• Non-S Type

Light vs Position in WLS Fibers
Attenuation curves for several fibers in the same
batch from Kuraray (batch 1000m)
Typical long attenuation length 6 m
Light (arb. units)
Fiber spool in use on the glue machine.
Typical variation in light from far end is 3.
Variation in light from the far end of 8 m fibers
from one batch to another has a sigma of about
5.
Position (m)
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Module Components

• The scintillator modules are a laminate of
  scintillator strips (with WLS fiber glued into
  the groove) with aluminum skins.
• WLS fibers are routed through end manifolds to
  bulk optical connectors.
• The entire assembly is light-tight.

Optical connector
Module parts for straight-out manifold
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Clear Fiber
Coiled conduit with fibers (loose) inside.
shroud
shroud
connectors
Photo of a complete cable
Schematic of a Cable
20/28 Fibers per cable 1.2 mm diam. Kuraray
double clad fiber
Clear fiber cables transmit light from modules to
PMT boxes
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PMTs

• Hamamatsu R5900 series multi-anode PMTs have been
  selected
• 16 pixel tubes for the far detector (pixel size
  4mm x 4mm)
• 64 pixel tubes for the near detector (pixel size
  2mm x 2mm)
• Gain of 106 consistent to x2 (M16) or x3(M64)
• QE at 520 nm typically 13.5
• Good single pe peak
• Very fast signals and low time jitter.

Fiber Layout
16 mm
Cut-away view of R5900 series PMT
M16
M64
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PMT Measurements
10
PMT Boxes and Connectors
Cookie with fibers
PMT Mounting Components

• Far detector (shown)
• 3 M16 PMTs/box
• 8 fibers per pixel optical multiplexing
• Each box serves 2 planes (one side)

Alignment window (not installed)
Adjustable mounting bracket (alignment)
PMT jacket
M16 PMT
Spring loaded PMT base
Front-end electronics
Connector pair
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Light Injection System

• The light injection system provides short term
  PMT gain checks, linearity checks and monitoring
  of light transmission.
• 16 pulser boxes, 20 LEDs per box
• Light from each LED fanned out x 50
• Light distribution uniform to within a factor of
  2
• Up to 150 pes observed at PMT channels
• 12 bit resolution on amplitude control

Light Injection Prototype
PIN Diodes
Light fanout cone
Acrylic fibers to distribute LED light
Module End Manifold
Light fanout cone
WLS Fibers
LED Pulse Boxes
Light Injection Pockets
Schematic of Light Injection System
Relative light in fibers
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Calibration Detector

• The calibration detector is a small version of
  the big detectors to be exposed in test beams
• 1 m square x 60 planes deep
• All technology as in MINOS near and far detectors
  (both technologies where there are differences.)
• Provide hadronic energy scale
• Detailed topology studies
• Calibration transported between detectors using
  cosmic ray muons

Waiting for drawing of detector.
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Automated Production Equipment
Automatic Fiber Gluing Machine Lays down bead
of glue, unrolls fiber from spool, pushes fiber
into glue in groove and covers the groove with a
reflector.
Automated Module Mapper with 28 strip-wide module
(8m x 1.2 m). Uses computer driven x-y
scanning table with 137Cs source.
Computer control and readout
Fiber spool
Glue dispenser
x-y bridge
Gluing apparatus
source
Module
28 strip-wide module
Light injection manifold
Optical connector
PMT Box
Fibers at connector
Clear fiber cable
14
Module Factories
Module on shuttle table
Module with fibers glued in.
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Assembled Scintillator Plane
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System Light Output
Number of observed photoelectrons
Number of observed photoelectrons
A typical 45o module
One of the best modules
Note The drop in light at the two ends is due
to different lengths of strips at the ends.
Distance along the module (m)
Distance along the module (m)
Light output vs position of cosmic ray muons
passing nearly perpendicularly through a
scintillator module averaged over all strips
within a module. The light output is
measured using the full MINOS readout apparatus
(connectors, clear fibers, PMTs). The light read
from each end of a module is shown along with the
sum of light from each end.
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Module Mapper Results
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4PP Operations
Clear Fiber Cables
MUX Box
Trigger module
Module Manifolds
Trigger module
Connectors
Steel Octagon
Rabbit Crate
Downstream View
Edge View
Cosmic ray muons are readout using an external
trigger in the 4 Plane prototype (3 scintillator
planes). Results are consistent with previous
cosmic ray tests made one year earlier with the
modules horizontal in the cosmic ray test stand.
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Cosmic Ray Muons in the 4PP
Typical single photoelectron spectrum from light
injection
Number of observed photoelectrons per muon
(corrected to 1 cm thickness)
pedestal
single pe peak
Note The data are from a small section of the
4PP where the trigger counters cover.
Used to determine PMT gains
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Some Scintillator System Parameters

• Some major system features
• Extruded Polystyrene Scintillator 300 T, 600 km
  of 4.1x1.0 cm2 strips.
• WLS Fiber Kuraray double-clad 1.2 mm diam., 175
  ppm Y11, 780 km
• Scintillator Modules 20/28 strips wide and up to
  8m long. 4300 mods., 28,000 m2
• Clear Fiber Like WLS, no fluor, 1100 km of
  fiber built into cables with 20/28 fibers.
• PMTs
• Far detector Hamamatsu M16 with 8 fibers per
  pixel with fibers readout from each side of the
  detector. 3 tubes per plane, 1500 tubes
• Near detector Hamamatsu M64 with one fiber per
  pixel and fibers readout from one side of the
  detector (with reflectors on the far end). 200
  tubes.
• Light Injection Blue LED illumination of all WLS
  fibers to rapidly track PMT response.
• Performance Requirements
• Light output gt 4.7 observed pes on average for
  a MIP crossing.
• Time measurement s lt 5 ns per plane for MIP
  crossing.
• Calibration
• Relative near/far energy response to within 2.
• Absolute hadronic energy response to within 5.